A common use for crimping devices is to apply couplings to the ends of hydraulic hoses. A common form of coupling consists of a tubular body portion surrounded by a tubular shell portion, with an annular space between them. The end of a hose is pushed over the body portion into the space between it and the shell portion, and then the shell portion is crimped radially inwards to squeeze the end of the hose tightly between the shell portion and the body portion, thereby firmly securing the coupling to the hose.
It is well known that it is for practical purposes important that at the end of the crimping operation the outside of the crimped article should have been brought to a predetermined desired outside diameter.
British Patent Specification No. 962,094 describes a crimping device of a kind which has been commonly used but has various disadvantages. It is fitted with a gauging device which is intended to enable crimping accurately to a given outside diameter. However, the gauging device is located well off the central axis of the crimping device and for that reason its accuracy is adversely affected by any mis-alignment or distortion of the components of the device. Additionally, it is difficult to set the rotatable gauging element 22 accurately by eye. To assist in this, in practice a short graduated scale about 1" long has been located on the device adjacent to member 22 so that the member 22 can be rotated until its top corresponds with any desired selected one of the markings on the scale. However, because of the shortness of the scale this does not enable the member 22 to be set very accurately. Furthermore, the setting of the gauging member 22 did not actually predetermine the outside diameter that would be achieved at the end of the crimping operation, but only provided the operator of the device with a reference against which he would have to judge by eye when the desired outer diameter had been reached, recognising this situation as being when the top of the other gauging member 21 had reached a position flush with the top of the gauging member 22. He would have to stop the operation of the device as soon as he perceived that this situation had been reached. Of course, judgement and action of this type is not of great accuracy.
Canadian Pat. No. 896,222 discloses a crimping device which has similar problems.